CN103699439A - Device and method for calculating tiles in electronic map visual area - Google Patents

Abstract

The invention discloses a device and method for calculating tiles in the visible area of an electronic map. The method includes: converting and obtaining the pixel of the center point according to the geographic location coordinates of the center point of the map visible area and the current display level of the map Coordinates; according to the current display level of the map, get the pixel size of a single tile at the current display level; get the pixel coordinates of two opposite vertices of the map visible area according to the pixel size of the map visible area and the pixel coordinates of the center point ; and obtain the tile number in the visible area according to the pixel coordinates of two opposite vertices in the visible area of the map and the pixel size of a single tile at the current display level. The present invention calculates the number of tiles in the visible area through geographic location coordinates and display levels, thereby accurately calculating the number of tiles in the visible area, and solves the problem of the accuracy and speed of tile acquisition operations. good question.

Description

A device and method for calculating tiles in the visible area of an electronic map

technical field

The invention relates to the technical field of electronic maps, in particular to a device for calculating tiles in a visible area of an electronic map and a method for calculating tiles in a visible area of an electronic map.

Background technique

In the current application of electronic maps, the specific storage form of storing tiles by the server is to store the tiles with pixel coordinates as indexes. The method for the client to request the tiles in the visible area of the electronic map is to send a download tile request to the server by using the pixel coordinates, and the server gets the tiles according to the pixel coordinates and returns the tiles to the client. However, this method , not only the processing capacity of the server is large, but also the accuracy and operation speed of the tile acquisition operation are not good.

Contents of the invention

In view of the above problems, the present invention is proposed to provide a device for calculating tiles in the visible area of an electronic map and a corresponding method for calculating tiles in the visible area of an electronic map that overcome the above problems or at least partially solve the above problems .

According to one aspect of the present invention, a device for calculating tiles in the visible area of an electronic map is provided, the device includes: a fixed-point arithmetic unit, adapted to calculate the tiles according to the geographic location coordinates of the center point of the visible area of the map and the current map location. Display level, converted to obtain the pixel coordinates of the center point; tile analysis unit, suitable for obtaining the pixel size of a single tile at the current display level according to the current display level of the map; vertex analysis unit, suitable for pixels in the visible area of the map The size and the pixel coordinates of the center point are used to obtain the pixel coordinates of two opposite vertices of the visible area of the map; the tile operation unit is adapted to obtain the pixel coordinates of two opposite vertices of the visible area of the map and the single The pixel dimensions of the tile get the tile number within the viewable area.

Optionally, the vertex analysis unit is adapted to obtain the horizontal index number and the vertical index number of the tile where the two opposite vertices are located; The index number and the vertical index number between the vertical index numbers of the tiles where the two opposite vertices are located, that is, the tile numbers in the visible area of the map are obtained; wherein, the tile operation unit is suitable for the The vertices use the pixel coordinates of the vertices to subtract the pixel coordinates of the origin of the map to obtain the difference of the abscissa and the difference of the ordinate, divide the difference of the abscissa by the pixel width of a single tile to obtain the horizontal index number, and use the ordinate Divide the difference by the pixel height of a single tile to get the vertical index number, so as to get the horizontal index number and vertical index number of the tile where the two opposite vertices are located.

Optionally, the device further includes: a preloading tile computing unit, adapted to calculate the preloading tile corresponding to the visible area in at least one preloading level according to the geographic position coordinates of the center point of the visible area of the map and the preloading level or, suitable for performing division and rounding or multiplication on the tile numbers in the visible area of the map at the current display level according to the level difference between the preload level and the current display level to calculate at least one preload level The numbers of the preloaded tiles corresponding to the tiles in the visible area; wherein, the preloaded level is at least one level whose difference from the current display level is within a set range.

Optionally, the preloading tile computing unit is adapted to convert the pixel coordinates of the center point according to the geographic location coordinates and the preloading level of the center point of the visible area of the map; obtain the preloading level according to the preloading level of the map The pixel size of a single tile; according to the pixel size of the visible area of the map and the pixel coordinates of the center point, the pixel coordinates of two opposite vertices of the visible area of the map are obtained; and according to the two opposite vertices of the visible area of the map The pixel coordinates of and the pixel dimensions of a single tile of the preload level get the number of the preload tile corresponding to the viewable area in the preload level.

Optionally, if the preloading level is higher than the current display level, the preloading tile computing unit is adapted to divide the horizontal index number and the vertical index number of the tiles in the visible area of the map at the current display level by m And rounded, wherein, m= ^2k , k is a natural number, indicating the level difference between the preloading level and the current display level; if the preloading level is lower than the current display level, then the preloading tile operation unit is suitable for Multiply the horizontal and vertical index numbers of tiles in the visible area of the map at the current display level by p and obtain p adjacent index numbers according to the multiplication results, where p=2 ^q , q is a natural number, indicating The level difference between the currently displayed level and the preloaded level.

Optionally, the two opposite vertices of the viewable map area include: an upper left vertex and a lower right vertex of the viewable map area, or, an upper right vertex and a lower left vertex of the viewable map area.

Optionally, the fixed-point arithmetic unit is further adapted to convert to obtain the pixel coordinates of the zoom focus center according to the geographic location coordinates of the zoom focus center of the map and the target display level after the map is zoomed when receiving an instruction to zoom the map; The tile analysis unit is further adapted to obtain the pixel size of a single tile at the target display level according to the target display level; the vertex analysis unit is further adapted to obtain the pixel size of the visible area of the map and the zoom focus center The pixel coordinates obtain the pixel coordinates of two relative vertices of the visible area after the map is zoomed; The pixel dimensions of a single tile at a level get the number of tiles within the viewable area of the map after zooming.

According to another aspect of the present invention, there is provided a method for calculating the tiles in the visible area of the electronic map, the method includes: according to the geographical location coordinates of the center point of the visible area of the map and the current display level of the map, the conversion is obtained The pixel coordinates of the center point; according to the current display level of the map, the pixel size of a single tile at the current display level is obtained; according to the pixel size of the visible area of the map and the pixel coordinates of the central point, two relative tiles of the visible area of the map are obtained The pixel coordinates of the vertices; and the tile number in the visible area according to the pixel coordinates of two opposite vertices in the visible area of the map and the pixel size of a single tile at the current display level.

Optionally, obtaining the tile numbers in the map visible area according to the pixel coordinates of two opposite vertices of the map visible area and the pixel size of a single tile to be displayed includes: obtaining the location of the two opposite vertices The horizontal index number and vertical index number of the tile; and the horizontal index number between the horizontal index numbers of the tiles where the two opposite vertices are located and the vertical index number between the vertical index numbers of the tiles where the two opposite vertices are located The vertical index number between them, that is, to obtain the tile number in the visible area of the map; wherein, the obtaining the horizontal index number and the vertical index number of the tile where the two opposite vertices are located specifically includes: respectively using the The pixel coordinates of the vertex minus the pixel coordinates of the origin of the map get the difference between the abscissa and the ordinate, divide the difference of the abscissa by the pixel width of a single tile to get the horizontal index number, and use the difference of the ordinate Divide by the pixel height of a single tile to get the vertical index number.

Optionally, the method further includes: calculating the number of preloaded tiles corresponding to the visible area in at least one preloading level according to the geographic location coordinates of the central point of the visible area of the map and the preloading level; or according to the preloading level The level difference between the current display level and the tile numbers in the visible area of the map under the current display level are divided and rounded or multiplied, and the preloaded values corresponding to the tiles in the visible area in at least one preloaded level are calculated. The number of the tile to be loaded; wherein, the preloading level is at least one level that is different from the current display level within a set range.

Optionally, the calculating the number of preloaded tiles corresponding to the visible area in at least one preloading level according to the geographic location coordinates of the central point of the map visible area and the preloading level specifically includes: according to the map visible area The geographic location coordinates of the center point of the map and the preloading level are converted to obtain the pixel coordinates of the center point; according to the preloading level of the map, the pixel size of a single tile of the preloading level is obtained; according to the pixel size of the visible area of the map and the center point The pixel coordinates of the two opposite vertices of the visible area of the map are obtained; and the pixel coordinates of the two opposite vertices of the visible area of the map and the pixel size of a single tile of the preloaded level are obtained in the preloaded level The number of the preloaded tile corresponding to the viewable area.

Optionally, according to the level difference between the preloading level and the current display level, the numbers of the tiles in the visible area of the map under the current display level are divided and rounded or multiplied, including: if the preloading level is high At the current display level, divide the horizontal and vertical index numbers of the tiles in the visible area of the map at the current display level by m and round up, where m=2 ^k , k is a natural number, indicating the preloading level The difference between the level and the current display level; if the preload level is lower than the current display level, multiply the horizontal index number and vertical index number of the tile in the visible area of the map under the current display level by p and calculate the multiplication result Get p adjacent index numbers, where, p=2 ^q , q is a natural number, indicating the level difference between the current display level and the preloading level.

Optionally, the two opposite vertices of the viewable map area include: an upper left vertex and a lower right vertex of the viewable map area, or, an upper right vertex and a lower left vertex of the viewable map area.

Optionally, the method further includes: when receiving an instruction to zoom the map, convert to obtain the pixel coordinates of the zoom focus center according to the geographic location coordinates of the zoom focus center of the map and the target display level after the map is zoomed; , to get the pixel size of a single tile at the target display level; according to the pixel size of the visible area of the map and the pixel coordinates of the zoom focus center, to get the pixel coordinates of two opposite vertices of the visible area of the map after zooming; and according to The pixel coordinates of two opposite vertices of the viewable area after the map is zoomed and the pixel size of a single tile at the target display level obtain the number of the tiles in the viewable area after the map is zoomed.

According to the device for calculating the tiles in the visible area of the electronic map and the method for calculating the tiles in the visible area of the electronic map according to the present invention, the numbers of the tiles in the visible area are calculated through the geographic location coordinates and the display level, In this way, the numbers of the tiles in the visible area are accurately calculated, and the problem of poor accuracy and operation speed of the tile acquisition operation is solved.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the specific embodiments of the present invention are enumerated below.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiment. The drawings are only for the purpose of illustrating a preferred embodiment and are not to be considered as limiting the invention. Also throughout the drawings, the same reference numerals are used to designate the same parts. In the attached picture:

FIG. 1 shows a flowchart of a method for calculating tiles in a visible area of an electronic map according to a first embodiment of the present invention;

FIG. 2 shows a detailed flowchart of step S400 in FIG. 1;

FIG. 3 shows a flow chart of a method for calculating tiles in the visible area of an electronic map according to a second embodiment of the present invention;

Fig. 4 shows the detailed flowchart of step S500' among Fig. 3;

FIG. 5 shows a flow chart of a method for calculating tiles in the visible area of an electronic map according to a third embodiment of the present invention;

FIG. 6 shows a block diagram of an apparatus for calculating tiles within a visible area of an electronic map according to a first embodiment of the present invention;

FIG. 7 shows a block diagram of a method for calculating tiles in the visible area of an electronic map according to a second embodiment of the present invention; and

Fig. 8 shows a schematic diagram of an electronic map client implemented according to the present invention.

Detailed ways

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided for more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

It should be noted that the electronic map tiles are the pictures in the grid map. These pictures are spliced into a complete electronic map according to certain rules, and the electronic map is enlarged (see Baidu map, Tencent map and other electronic map network clients, Click the zoom-in button, which is the "+" button, it can be seen that in the field of electronic map technology, zooming in on the map means that the geographical range displayed in the same electronic map display range is small, and the geographic details are more detailed), and lower-level tiles will be displayed. The map range represented by a single tile at a higher level is larger than that represented by a single tile at a lower level, for example, a tile at a higher level (such as level 16) in an adjacent level is equivalent to a lower level The map range represented by the four tiles of the level (for example, level 17). Among the two levels with a level difference of 2, one tile of the higher level (for example, level 16) is equivalent to the tile of the lower level (for example, level 18 Level) The map range represented by sixteen tiles.

Fig. 1 shows a flowchart of a method for calculating tiles in a visible area of an electronic map according to a first embodiment of the present invention. The method includes steps S100 to S400 as described below:

S100. According to the geographic location coordinates of the center point of the visible area of the map and the current display level of the map, convert to obtain the pixel coordinates of the center point. In this embodiment, the geographic location coordinates of the central point of the visible area of the map are latitude and longitude coordinates or the coordinates obtained by projecting the latitude and longitude coordinates onto the planar map through a projection algorithm, and can be converted through the geographic location coordinates and the current display level of the map Get the pixel coordinates (eg X-Y coordinates) of the center point.

S200. Obtain the pixel size of a single tile at the current display level according to the current display level of the map.

Preferably, in this embodiment, in order to display the information on the map in more detail and comprehensively, the storage of the electronic map adopts a hierarchical tile mechanism, and the map is divided into multiple levels for storage, and the corresponding grid map is stored under each level Tiles, taking tiles under two adjacent display levels as an example, display four adjacent tiles under the lower display level (that is, four adjacent tiles in the shape of "Tian" in 2×2) Corresponds to a tile under a display level with a high display level; taking a two-layer tile with a level difference of 2 as an example, sixteen adjacent tiles under a display level with a low display level (that is, 4×4 Sixteen adjacent tiles) correspond to a tile under a display level with a higher display level. Therefore, the pixel size of a single tile at different levels is different. According to the current display level of the map, the pixel size of a single tile at the current display level, such as pixel width and pixel height, can be obtained.

S300. According to the pixel size of the visible area of the map and the pixel coordinates of the center point, obtain the pixel coordinates of two opposite vertices of the visible area of the map. In this embodiment, it is assumed that the visible area of the map is square and the pixel size is fixed. Of course, even if the pixel size of the visible area is variable, those skilled in the art can detect the pixel size of the visible area. In this embodiment, the two opposite vertices of the map visible area include the upper left vertex and the lower right vertex of the map visible area, or the upper right vertex and the lower left vertex of the map visible area, through which two relative vertices can uniquely Determines the extent of the visible area of the map.

S400. Obtain the tile number in the visible area according to the pixel coordinates of two opposite vertices in the visible area of the map and the pixel size of a single tile at the current display level.

According to the principle of projection, overlapping points in the two maps before and after zooming represent the same geographic location. In this embodiment, the point whose geographic location remains unchanged before and after the zooming of the map is defined as the zoom focus center. According to the geographic location coordinates of the zoom focus center (that is, longitude and latitude coordinates) and the target display level after the map is zoomed, the pixel coordinates (for example, X-Y coordinates) of the center of the zoom focus can be obtained. The zoom focus center of this embodiment can be the position of the mouse when receiving the zoom map instruction input by the user through the mouse wheel, or when receiving the user input through the page buttons (such as "+" and "-") The zoom map command can be the center of the map. Calculating the numbers of the tiles in the visible area after the map is zoomed based on the zoom focus center can simplify the calculation process and reduce the calculation amount.

Therefore, the method of this embodiment further includes the following steps, to calculate the number of tiles in the visible area after the map is zoomed when receiving the zoom map instruction input by the user: when receiving the zoom map instruction, according to The geographic location coordinates of the zoom focus center of the map and the target display level after zooming the map are converted to obtain the pixel coordinates of the zoom focus center; according to the target display level, the pixel size of a single tile at the target display level is obtained; according to the visible area of the map The pixel size of the pixel size and the pixel coordinates of the center of the zoom focus to obtain the pixel coordinates of the two opposite vertices of the visible area after the map is zoomed; and the pixel coordinates and target display of the two opposite vertices of the visible area after the map is zoomed The pixel dimensions of a single tile at a level get the number of tiles within the viewable area of the map after zooming.

FIG. 2 shows a detailed flowchart of step S400 in FIG. 1 . Including steps S410 and S420 as described below:

S410. Obtain horizontal index numbers and vertical index numbers of tiles where two opposite vertices are located. Specifically, the pixel coordinates of the vertices are used to subtract the pixel coordinates of the origin of the map from the two opposite vertices to obtain the difference between the abscissa (for example, the X coordinate of the X-Y coordinate system) and the ordinate (for example, the X-Y coordinate system The difference between Y coordinates); further divide the difference in abscissa by the pixel width of a single tile to obtain the horizontal index number, and divide the difference in ordinate by the pixel height of a single tile to obtain the vertical index number.

S420. Select the horizontal index numbers between the horizontal index numbers of the tiles where the two opposing vertices are located (including the horizontal index numbers of the tiles where the two opposing vertices are located) and the tiles where the two opposing vertices are located The vertical index numbers between the vertical index numbers (including the vertical index numbers of the tiles where the two opposite vertices are located), that is, the tile numbers in the visible area of the map. Through step S420, the serial numbers of the tiles in the square viewable area are obtained.

Fig. 3 shows a flowchart of a method for calculating tiles in a visible area of an electronic map according to a second embodiment of the present invention. The second embodiment includes step S100' to step S500', wherein step S100' to step S400' are respectively the same as step S100 to step S400 in the first embodiment, and will not be repeated here.

Step S500' is: calculate the number of preloaded tiles corresponding to the visible area in at least one preloaded level according to the geographic location coordinates of the center point of the visible area of the map and the preloaded level. The preload level is at least one level that is different from the current display level within the set range. For example, assuming that the current display level is level 10, if the set range is at most 3 levels higher than the current display level and higher than the current display level 2 levels lower, the preload levels include levels 9, 8, and 7 higher than level 10, and levels 11 and 12 lower than level 10.

Fig. 4 shows a detailed flowchart of step S500' in Fig. 3 . Step S500' includes steps S510' to S540' as follows:

S510'. According to the geographic location coordinates and the preloading level of the center point of the visible area of the map, convert to obtain the pixel coordinates of the center point. In this embodiment, the geographic location coordinates of the central point of the visible area of the map are latitude and longitude coordinates or the coordinates obtained by projecting the latitude and longitude coordinates onto the planar map through a projection algorithm. Pixel coordinates (e.g. X-Y coordinates) of the center point at the preloaded display level.

S520'. According to the preloading level of the map, obtain the pixel size of a single tile of the preloading level. According to the preloading level of the map, the pixel size of a single tile at the preloading level can be obtained, such as pixel width and pixel height.

S530'. According to the pixel size of the map visible area and the pixel coordinates of the center point, obtain the pixel coordinates of two opposite vertices of the map visible area. The two opposite vertices of the visible area of the map include the upper left vertex and the lower right vertex of the visible area of the map, or the upper right vertex and the lower left vertex of the visible area of the map. The visible area of the map can be uniquely determined by two opposite vertices range.

S540', according to the pixel coordinates of two opposite vertices of the visible area of the map and the pixel size of a single tile of the preloaded level, obtain the serial number of the preloaded tile corresponding to the visible area in the preloaded level. The specific method for implementing step S540' is similar to steps S410 and S420 shown in FIG. 2 , and will not be repeated here.

Further, the above step S500' also includes the operation of obtaining the numbers of the tiles around the preloaded tiles at the preloaded level according to the obtained numbers of the preloaded tiles. Specifically, the obtained horizontal index numbers and vertical index numbers are appropriately expanded.

Fig. 5 shows a flowchart of a method for calculating tiles in a visible area of an electronic map according to a third embodiment of the present invention. The third embodiment includes step S100'' to step S500'', wherein step S100'' to step S400'' are respectively the same as step S100 to step S400 in the first embodiment, and will not be repeated here.

Step S500'' is: according to the level difference between the preloading level and the current display level, perform division and rounding or multiplication on the tile numbers in the visible area of the map at the current display level, and calculate the difference between at least one preloading level and The number of the preloaded tile corresponding to the tile in the visible area. The preloading level is at least one level whose level difference from the current display level is within a set range.

Specifically, in step S500'', according to the level difference between the preloading level and the current display level, the division and rounding or multiplication of the tile numbers in the visible area of the map at the current display level includes: if the preloading level If it is higher than the current display level, divide the horizontal and vertical index numbers of the tiles in the visible area of the map at the current display level by m and round up. Those skilled in the art can understand that the specific rounding algorithm can be selected according to the index number of the origin of tile segmentation. If the index number of the origin of tile segmentation is zero, it can be rounded down (similar to floor function), otherwise it is rounded up (similar to the ceiling function). Wherein, m=2 ^k , k is a natural number, representing the level difference between the preloading level and the current display level. If the preloading level is lower than the current display level, multiply the horizontal and vertical index numbers of the tiles in the visible area of the map at the current display level by p and obtain p adjacent index numbers according to the multiplication results. The method is corresponding to the above-mentioned rounding algorithm, wherein, p=2 ^q , and q is a natural number, indicating the level difference between the current display level and the preloading level. Compared with step S500' of the second embodiment, step S500'' of the third embodiment reduces computational complexity while ensuring accuracy.

Further, the above step S500'' also includes the operation of obtaining the serial numbers of the tiles around the preloaded tiles at the preloaded level according to the obtained serial numbers of the preloaded tiles. Specifically, the obtained horizontal index numbers and vertical index numbers are appropriately expanded.

It should be noted that if the preloading level is higher than the current display level, the geographic area corresponding to each preloading tile is larger than the geographic area corresponding to each target tile and is n times the geographic area corresponding to each target tile , n=4 ^k , k is a natural number, representing the level difference between the preloading display level and the target display level. If the preload level is lower than the current display level, the geographic area corresponding to each preload tile is smaller than the geographic area corresponding to each target tile and is 1/r of the geographic area corresponding to each target tile, where r =4 ^q , q is a natural number, indicating the level difference between the current display level and the preloaded level.

Further, in conjunction with the operation of loading and displaying the electronic map, the technical effect achieved by calculating the number of preloaded tiles in step S500' of the second embodiment of the present invention and step S500'' of the third embodiment of the present invention, specifically reducing The technical effect of the probability that the electronic display window is blank when the electronic map client zooms or pans the electronic map.

If you analyze the relationship between the number of requests for loading tiles and the time of the electronic map client in a long enough time range, you will often find that the number of requests for loading tiles in some time periods is small (idle time period, idle-time partition), and there are many requests to load tiles in a relatively short period of time. By calculating the number of preloaded tiles, the electronic map client can call the idle thread to preload some or all of the above preloaded tiles during the idle time period. piece.

Furthermore, when the electronic map client receives the electronic map interaction instruction input by the user and zooms or pans the electronic map according to the interactive instruction, it calculates the target display level after the response is completed (for example, the map zoom-in operation is completed) (if the map is panned, The target display level is the current display level), load and render to display the target tiles under the target display level. If the above-mentioned preloaded tiles already loaded exist in the set of target tiles, the overall response speed is improved.

Furthermore, it is possible to calculate a blur level higher than the target display level, select the blur tile corresponding to the target tile in the blur level, and enlarge the blur tile to obtain a lower-definition map. After obtaining the target level tile , load and display the target level tiles to replace the enlarged blurry tiles at the corresponding positions to obtain a clear map. Since the overall number of blur tiles is smaller than the overall number of target tiles, the response speed is faster. If there are already loaded preloaded tiles in the set of fuzzy tiles, the overall response speed will be further improved. Those skilled in the art can easily understand that when the map is zoomed in or panned, the probability of using the above preloaded tiles is high . Therefore, step S500' in the second embodiment of the present invention and step S500'' in the third embodiment of the present invention reduce the probability that the electronic display window is blank when the electronic map client zooms or pans the electronic map by calculating the number of preloaded tiles.

Fig. 6 shows a block diagram of an apparatus for calculating tiles in a visible area of an electronic map according to a first embodiment of the present invention. The device includes a fixed point operation unit 100 , a tile analysis unit 200 , a vertex analysis unit 400 and a tile operation unit 400 .

The fixed-point calculation unit 100 is adapted to obtain the pixel coordinates of the center point through conversion according to the geographic location coordinates of the center point of the visible area of the map and the current display level of the map. In this embodiment, the geographic location coordinates of the central point of the map visible area are latitude and longitude coordinates or the coordinates that project the latitude and longitude coordinates onto the planar map through a projection algorithm. The fixed-point arithmetic unit 100 uses the geographic location coordinates and the current display level of the map, The pixel coordinates (such as X-Y coordinates) of the center point can be converted.

The tile analysis unit 200 is adapted to obtain the pixel size of a single tile at the current display level according to the current display level of the map. In this embodiment, the pixel size of a single tile at different levels is different, and the tile analysis unit 200 can obtain the pixel size of a single tile at the current display level, such as pixel width and pixel height, according to the current display level of the map.

The vertex analysis unit 300 is adapted to obtain the pixel coordinates of two opposite vertices of the map viewable area according to the pixel size of the map viewable area and the pixel coordinates of the central point. The two relative vertices of the map visible area in this embodiment include: the upper left vertex and the lower right vertex of the map visible area, or, the upper right vertex and the lower left vertex of the map visible area, which can be unique through two relative vertices accurately determine the range of the visible area of the map.

The tile computing unit 400 is adapted to obtain the tile number in the visible area according to the pixel coordinates of two opposite vertices in the visible area of the map and the pixel size of a single tile at the current display level.

The vertex analysis unit 300 of this embodiment is adapted to obtain the horizontal index number and the vertical index number of the tile where the two opposite vertices are located; the tile operation unit 400 is adapted to select the tile where the two opposite vertices are located. The horizontal index numbers between the horizontal index numbers and the vertical index numbers between the vertical index numbers of the tiles where the two opposite vertices are located are the tile numbers in the visible area of the map.

More specifically, the vertex analysis unit 300 is adapted to use the pixel coordinates of the vertex minus the pixel coordinates of the origin of the map to obtain the difference between the abscissa (for example, the X coordinate of the X-Y coordinate system) and the ordinate (for example, , the Y coordinate of the X-Y coordinate system), divide the difference of the abscissa by the pixel width of a single tile to obtain the horizontal index number, and divide the difference of the ordinate by the pixel height of a single tile to obtain the vertical index number, Thus, the horizontal index numbers and the vertical index numbers of the tiles where the two opposite vertices are located are obtained.

According to the principle of projection, overlapping points in the two maps before and after zooming represent the same geographic location. The zoom focus center in this embodiment is a point whose geographic location remains unchanged before and after zooming the map. The geographic location coordinates (that is, latitude and longitude coordinates) and the target display level after the map is zoomed can obtain the pixel coordinates (for example, X-Y coordinates) of the zoom focus center. Calculating the numbers of the tiles in the visible area after the map is zoomed based on the zoom focus center can simplify the calculation process and reduce the calculation amount.

Therefore, in this embodiment, the fixed-point arithmetic unit 100 is further adapted to convert and obtain the pixel coordinates of the zoom focus center according to the geographic location coordinates of the zoom focus center of the map and the target display level after zooming the map when receiving an instruction to zoom the map . The tile analysis unit 200 is further adapted to obtain the pixel size of a single tile at the target display level according to the target display level. The vertex analysis unit 300 is further adapted to obtain the pixel coordinates of two opposite vertices of the visible area after the zoomed map according to the pixel size of the visible area of the map and the pixel coordinates of the zoom focus center. The tile operation unit 400 is further adapted to obtain the pixel coordinates of two opposite vertices of the viewable area after the map is zoomed and the pixel size of a single tile at the target display level to obtain the tiles in the viewable area after the map is zoomed. serial number.

Fig. 7 shows a block diagram of a method for calculating tiles in a visible area of an electronic map according to a second embodiment of the present invention. The second embodiment of the present invention is substantially the same as the above-mentioned first embodiment, except that a preloaded tile calculation unit 500 is further included.

The preloading tile operation unit 500 is adapted to calculate the number of the preloading tile in the preloading level, wherein the preloading level is at least one level whose level difference from the current display level is within a set range. There are two specific implementations of the preloading tile computing unit 500 in this embodiment. The first specific implementation is to calculate at least one preloading level and map The number of the preloaded tile corresponding to the visible area. Specifically, the preloading tile computing unit 500 converts the pixel coordinates of the center point according to the geographic location coordinates and the preloading level of the center point of the visible area of the map; obtains a single tile of the preloading level according to the preloading level of the map The pixel size of the map; according to the pixel size of the visible area of the map and the pixel coordinates of the central point, the pixel coordinates of the two opposite vertices of the visible area of the map are obtained; and according to the pixel coordinates of the two opposite vertices of the visible area of the map and The pixel dimensions of a single tile of a preload level get the number of the preload tile corresponding to the viewable area in the preload level.

The two relative vertices of the map visible area include: the upper left vertex and the lower right vertex of the map visible area, or the upper right vertex and the lower left vertex of the map visible area, which can be uniquely determined by the two relative vertices The extent of the visible area of the map.

The second specific implementation of the preloading tile computing unit 500 in this embodiment is to divide and round the tile numbers in the visible area of the map at the current display level according to the level difference between the preloading level and the current display level An operation or a multiplication operation to calculate the number of the preloaded tile corresponding to the tile in the viewable area in at least one preloaded level. Specifically, if the preload level is higher than the current display level, the preload tile computing unit 500 is adapted to divide the horizontal index numbers and vertical index numbers of the tiles in the visible area of the map at the current display level by m and take Integer, wherein, m=2 ^k , k is a natural number, representing the level difference between the preloading level and the current display level; if the preloading level is lower than the current display level, the preloading tile computing unit 500 is suitable for converting The horizontal and vertical index numbers of the tiles in the visible area of the map under the level are multiplied by p respectively, and p adjacent index numbers are obtained according to the result of the multiplication operation, where, p=2 ^q , q is a natural number, indicating the current display level and the level difference between the preloaded level.

Further, the above-mentioned preloading tile calculation unit 500 further obtains the numbers of tiles around the preloading tile at the preloading level according to the obtained numbering of the preloading tiles. Specifically, the obtained horizontal index numbers and vertical index numbers are appropriately expanded.

Fig. 8 shows a schematic diagram of an electronic map client implemented according to the present invention. Through the device for calculating the tiles in the visible area of the electronic map and the method for calculating the tiles in the visible area of the electronic map of the present invention, the accuracy of the tiles obtained by the electronic map client is better, and the speed of obtaining tiles is faster , zooming and panning the image is more responsive.

It should be noted:

The algorithms and displays presented herein are not inherently related to any particular computer, virtual system, or other device. Various generic systems can also be used with the teachings based on this. The structure required to construct such a system is apparent from the above description. Furthermore, the present invention is not specific to any particular programming language. It should be understood that various programming languages can be used to implement the content of the present invention described herein, and the above description of specific languages is for disclosing the best mode of the present invention.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure the understanding of this description.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, in order to streamline this disclosure and to facilitate an understanding of one or more of the various inventive aspects, various features of the invention are sometimes grouped together in a single embodiment, figure, or its description. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

Those skilled in the art can understand that the modules in the device in the embodiment can be adaptively changed and arranged in one or more devices different from the embodiment. Modules or units or components in the embodiments may be combined into one module or unit or component, and furthermore may be divided into a plurality of sub-modules or sub-units or sub-assemblies. All features disclosed in this specification (including accompanying claims, abstract and drawings), as well as any method or method so disclosed, may be used in any combination, except that at least some of such features and/or processes or units are mutually exclusive. All processes or units of equipment are combined. Each feature disclosed in this specification (including accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Furthermore, those skilled in the art will understand that although some embodiments described herein include some features included in other embodiments but not others, combinations of features from different embodiments are meant to be within the scope of the invention. and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.

The various component embodiments of the present invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) can be used in practice to implement some or all of the components in the device for calculating tiles in the visible area of an electronic map according to an embodiment of the present invention some or all of the features. The present invention can also be implemented as an apparatus or an apparatus program (for example, a computer program and a computer program product) for performing a part or all of the methods described herein. Such a program for realizing the present invention may be stored on a computer-readable medium, or may be in the form of one or more signals. Such a signal may be downloaded from an Internet site, or provided on a carrier signal, or provided in any other form.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The use of the words first, second, and third, etc. does not indicate any order. These words can be interpreted as names.

Claims (10)

1. A device for calculating tiles in the visible area of an electronic map, the device comprising: The fixed-point arithmetic unit is adapted to convert the pixel coordinates of the center point according to the geographic location coordinates of the center point of the visible area of the map and the current display level of the map; The tile analysis unit is adapted to obtain the pixel size of a single tile at the current display level according to the current display level of the map; The vertex analysis unit is adapted to obtain the pixel coordinates of two opposite vertices of the map visible area according to the pixel size of the map visible area and the pixel coordinates of the center point; The tile operation unit is adapted to obtain the tile number in the visible area according to the pixel coordinates of two opposite vertices in the visible area of the map and the pixel size of a single tile at the current display level. 2. The device according to claim 1, wherein the two opposite vertices of the visible map area include: an upper left vertex and a lower right vertex of the map visible area, or, an upper right vertex and a lower left vertex of the map visible area vertex. 3. Apparatus according to claim 1 or 2, wherein, The fixed-point arithmetic unit is further adapted to convert and obtain the pixel coordinates of the zoom focus center according to the geographical position coordinates of the zoom focus center of the map and the target display level after the map zoom when receiving the command to zoom the map; The tile analysis unit is further adapted to obtain the pixel size of a single tile at the target display level according to the target display level; The vertex analysis unit is further adapted to obtain the pixel coordinates of two opposite vertices of the visible area after the zoomed map according to the pixel size of the visible area of the map and the pixel coordinates of the center of the zoom focus; The tile operation unit is further adapted to obtain the tiles in the visible area after the map is zoomed according to the pixel coordinates of two opposite vertices of the visible area after the zoomed map and the pixel size of a single tile at the target display level number. 4. A method for calculating tiles in the visible area of an electronic map, the method comprising: According to the geographic location coordinates of the center point of the visible area of the map and the current display level of the map, the pixel coordinates of the center point are obtained through conversion; According to the current display level of the map, get the pixel size of a single tile at the current display level; According to the pixel size of the visible area of the map and the pixel coordinates of the central point, pixel coordinates of two opposite vertices of the visible area of the map are obtained; and Get the tile number in the visible area according to the pixel coordinates of two opposite vertices in the visible area of the map and the pixel size of a single tile at the current display level. 5. The method according to claim 4, wherein the tile numbers in the map visible area are obtained according to the pixel coordinates of two opposite vertices of the map visible area and the pixel size of a single tile to be displayed, include: Get the horizontal index number and vertical index number of the tile where the two opposite vertices are located; and Select the horizontal index number between the horizontal index numbers of the tiles where the two opposite vertices are located and the vertical index number between the vertical index numbers of the tiles where the two opposite vertices are located, that is, the map visible area the tile number; Wherein, the obtaining the horizontal index number and the vertical index number of the tile where the two opposite vertices are located specifically includes: respectively using the pixel coordinates of the vertices to subtract the pixel coordinates of the origin of the map to obtain the difference in the abscissa coordinates of the vertices The difference between the horizontal coordinate and the vertical coordinate, the horizontal index number is obtained by dividing the difference of the horizontal coordinate by the pixel width of a single tile, and the vertical index number is obtained by dividing the difference of the vertical coordinate by the pixel height of a single tile. 6. The method according to claim 4 or 5, wherein the method further comprises: Calculate the number of preloaded tiles corresponding to the visible area in at least one preloaded level according to the geographic location coordinates of the center point of the visible area of the map and the preloaded level; or according to the level difference between the preloaded level and the current display level Perform division and rounding or multiplication on the tile numbers in the visible area of the map at the current display level, and calculate the number of preloaded tiles corresponding to the tiles in the visible area in at least one preloaded level; The above preloading level is at least one level whose level difference from the current display level is within a set range. 7. The method according to any one of claims 4-6, wherein the preloading level corresponding to the visible area in at least one preloading level is calculated according to the geographic position coordinates of the center point of the visible area of the map and the preloading level. The number of the loaded tile, including: According to the geographic location coordinates and preloading level of the center point of the visible area of the map, the pixel coordinates of the center point are obtained through conversion; According to the preloading level of the map, get the pixel size of a single tile at the preloading level; According to the pixel size of the visible area of the map and the pixel coordinates of the central point, pixel coordinates of two opposite vertices of the visible area of the map are obtained; and The number of the preloaded tile corresponding to the visible area in the preloaded level is obtained according to the pixel coordinates of two opposite vertices in the visible area of the map and the pixel size of a single tile in the preloaded level. 8. The method according to any one of claims 4-7, wherein, according to the level difference between the preloading level and the current display level, the numbers of the tiles in the visible area of the map at the current display level are divided by Rounding or multiplication operations, including: If the preloading level is higher than the current display level, divide the horizontal index number and vertical index number of the tile in the visible area of the map under the current display level by m and round up, where m=2 ^k , k is a natural number , indicating the level difference between the preload level and the current display level; If the preloading level is lower than the current display level, multiply the horizontal and vertical index numbers of the tiles in the visible area of the map at the current display level by p, and obtain p adjacent index numbers according to the multiplication results, where , p=2 ^q , q is a natural number, indicating the level difference between the current display level and the preloaded level. 9. The method according to any one of claims 4-8, wherein the two opposite vertices of the map viewable area include: the upper left vertex and the lower right vertex of the map viewable area, or, the map viewable area The upper right vertex and lower left vertex of . 10. The method according to any one of claims 4-9, wherein the method further comprises: When receiving an instruction to zoom the map, convert to obtain the pixel coordinates of the zoom focus center according to the geographic location coordinates of the zoom focus center of the map and the target display level after the map is zoomed; According to the target display level, get the pixel size of a single tile under the target display level; According to the pixel size of the visible area of the map and the pixel coordinates of the center of the zoom focus, the pixel coordinates of two opposite vertices of the visible area after the map is zoomed are obtained; and According to the pixel coordinates of two opposite vertices of the viewable area after the map is zoomed and the pixel size of a single tile at the target display level, the number of the tile in the viewable area after the map is zoomed is obtained.

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